Air War Against Pests

T. HE AIRPLANE holds a bright new hope in the farmers' uphill struggle with insects. Since 1922, when Department engineers and entomologists developed a practical method for dusting cottonfields with calcium arscnatc to protect the crop against the boll weevil, commercial airplane dusting has become routine, particularly in cultivated fields that spread over a wide area unbroken by trees or shrubs. Later, and in a more limited manner, the airplane has been used regularly and effectively to control malaria-carrying mosquitoes and pests that destroy shade trees and timber in forests where spraying from the ground is difficult and expensive. Working with State and commercial aircraft dusting companies and growers and, during the w^ar, with the Army, Navy, and Coast Guard, the Department has found practical ways to spray plants and trees from the air and with the use of DDT to combat adult mosquitoes and other insects. Before these tests had been run no practical means for destroying adult mosquitoes over large areas was known. By using a quart or two of a 5-percent DDT solution per acre we can reduce the adult mosquito population by nearly 100 percent in wooded areas in a few hours. Equipment for spraying can be installed easily in an airplane or a helicopter. In some designs the forward speed of the plane drives a small propeller attached to a pump, which provides the pressure needed to force the insecticidal solution from its holding tank through a special nozzle, or a series of nozzles, in the form of tiny droplets or a mist. Several types of distribution apparatus were improved and simplified for military needs during the war. Many of these lend themselves readily to agricultural use. The forerunner of these more recently developed mechanisms for distributing baits and dusts for insect control was de-